1. Field of the Invention
This document relates to a data correcting method capable of implementing an optimum picture quality according to surrounding conditions and a liquid crystal display using the same.
2. Discussion of the Related Art
A liquid crystal display (LCD) displays an image by controlling light transmittance of a liquid crystal layer through fields applied to the liquid crystal layer correspondingly according to video signals. Such an LCD includes a flat panel display device having the advantages of being small and thin and consuming less power, is used for mobile computers such as notebook computers or PCs, office automation equipment, audio/video players, and the like. In particular, an active matrix type LCD having switching elements formed at liquid crystal cells is advantageous for implementing video by actively controlling the switching elements.
Thin film transistors (TFTs) as shown in FIG. 1 are commonly used as the switching elements used for the active matrix type LCD. With reference to FIG. 1, in the active matrix type LCD, digital video data is converted into analog data voltage based on a gamma reference voltage and supplied to a data line DL and, at the same time, scan pulses are supplied to a gate line GL to charge a data voltage in a liquid crystal cell Clc. To this end, a gate electrode of the TFT is connected to the gate line GL, a source electrode of the TFT is connected to the data line DL, and a drain electrode of the TFT is connected to a pixel electrode of the liquid crystal cell Clc and to one electrode of a storage capacitor (Cst). A common electrode Vcom is supplied to a common electrode of the liquid crystal cell Clc. The storage capacitor Cst serves to charge the data voltage applied to the data line DL when the TFT is turned on, and uniformly maintain the voltage of the liquid crystal cell Clc. When the scan pulse is applied to the gate line GL, the TFT is turned on to form a channel between the source and drain electrodes to supply the voltage of the data line DL to the pixel electrode of the liquid crystal cell Clc. At this time, the arrangement of liquid crystal molecules of the liquid crystal cell is changed due to fields between the pixel electrode and the common electrode to modulate incident light.
Various techniques are being developed to enhance the picture quality of a display screen. However, although the physical display screen image has a wide gamut, a change in the surrounding environment of a device such as illuminance hinders a color image from being faithfully reproduced with its original brightness and color sense.
The picture quality of a color image generally depends on three types of color attributes of lightness, chroma, and hue angle. The hue angle represents how close to four primary colors of red, yellow, green, and blue, or to a color obtained by mixing adjacent two primary colors in a certain ratio a given color is seen. The lightness is a relative concept of brightness representing how intensely a given object emits light. Namely, the lightness may be defined as a relative brightness of a particular object with respect to the brightness of a white object (or a white-like object) when the white object and the particular object are illuminated in a similar manner. The chroma is a relative concept of colorfulness representing the degree indicated by a color tone attribute at a given color in its outward appearance. Namely, the chroma may be defined as a relative ratio of the brightness of the white object (or the white-like object) to the colorfulness of the given particular object when the particular object and the white object are illuminated in a similar manner.
The color attributes such as lightness, chroma and hue angle are sensitively reactive to a change in an ambient illuminance, so if an ambient illuminance changes, an observer is bound to receive the same color differently. For example, the observer receives the same color image as being brighter or clearer in a high illuminance state compared to a low illuminance state.
Recently, a Korean Patent Laid Open Publication No. 2005-0040296 has proposed a technique of adjusting the brightness of a backlight according to ambient illuminance. However, this technique simply adjusts a change in the brightness according to an ambient illuminance, without considering a change in a hue angle resulting from a change in illuminance. As a result, this related art cannot change an image to have an optimum lightness, chroma, and hue angle suitably according to a visual sensitivity of a person (e.g., a user) in an ambient illuminance environment, failing to improve a picture quality.